Water softeners of the "ion exchange" type typically include a resin tank through which hard water passes to exchange its "hard" ions of calcium and magnesium for the "soft" sodium ions from the resin bed. Regeneration of the resin bed is required periodically to remove the accumulation of hard ions and replenish the supply of soft ions. Regeneration is typically affected by flushing a brine solution through the resin bed. A water softener of this type is more fully described in U.S. Pat. No. 3,891,552 issued June 24, 1975 to William Pryor and James W. Kewley, entitled CONTROL VALVE FOR WATER SOFTENERS, the disclosure of which is incorporated herein by reference.
Modern water softeners of the type disclosed in U.S. Pat. No. 3,891,552 typically employ a brine tank which includes a reservoir and supply of salt disposed at a level above the bottom of the reservoir. A tube connected to a source of water establishes a path for water to flow to the reservoir. Upon the attainment of a predetermined level in the reservoir, the water reacts with the salt supply to produce a source of brine for regeneration of the resin bed. When regeneration is required, the brine is aspirated through the same tube that supplied water to the reservoir. The amount of water introduced to the brine tank after the regeneration cycle and the amount of brine aspirated from the tank during a regeneration cycle is controlled by a brine valve mechanism.
Commercially available water softeners generally include one or two tanks which contain the softening chemicals that form the resin beds. In a two tank water softener, one tank is regenerated and kept "off-line" while the other tank is "on-line". A control valve controls the communication of the tanks with the household water supply and controls the timing and sequence of regeneration. One such system and control valve is disclosed in U.S. Pat. No. 3,891,552. An improved control valve is described in U.S. Pat. No. 4,298,025. Both of these patents are owned by the present assignee and are herein incorporated by reference.
A prior art resin tank typically comprises an elongate cylinder in which the ion exchange resin is contained. A conduit, often called a riser pipe, extends downwardly from the top of the tank. A filter screen, mounted at the end of the conduit prevents the entry of resin into the conduit. An opening is formed in the top of the tank for discharging or admitting fluid depending on the direction of flow.
In many applications, the prior art water softeners such as the one described in the above referenced patent, performed satisfactorily. However, in some areas of the country "problem water" is encountered which is not easily treated by conventional water softening apparatus. In particular, in some regions, the water has a high iron content and low pH. When a typical water softening apparatus is used to treat this water the result is still considered unacceptable or only marginally acceptable. Although methods and apparatus are known for treating water having a high iron content and low pH, many if not most are considered uneconomical for home use or use a process that the average homeowner is not equipped to handle.